David B Elliott1, Alison Green. 1. Bradford School of Optometry and Vision Science, University of Bradford, Bradford, United Kingdom. d.elliott1@bradford.ac.uk
Abstract
PURPOSE: To determine whether the optical quality of near-vision ready-made spectacles (RMS) reaches the quality assurance levels required by the international standard ISO 16034:2002. METHODS: A total of 322 near-vision RMS of powers +2.50, +3.00, and +3.50 DS were randomly selected from high street stores in North East England. Assessments of the optical quality of the RMS were made, and the results were compared against the standards included in ISO 16034:2002 and the more lenient standards used to assess RMS in low-resource countries. RESULTS: Forty-eight percent of the 322 near-vision RMS failed to provide the optical quality required by international standards, with 62% of the +3.50 DS spectacles failing the requirements. This was principally due to a high prevalence of induced horizontal (60%) and vertical prism (32%) beyond the tolerance levels stipulated in ISO 16034:2002. The figures were similar when the more lenient standards used to assess RMS in low-resource countries were used due to RMS centration distances that were too large. CONCLUSIONS: There is a large prevalence of significant amounts of induced horizontal and vertical prism in higher powered near-vision RMS such as +3.50 DS. Given that the need for high-powered RMS indicates the presence of hyperopia and/or age-related eye disease in addition to presbyopia, it may be appropriate to restrict the sale of RMS to optical powers of +1.00 to +2.50 DS, which would contain much fewer errors. We also strongly recommend that manufacturers use a centration distance for near-vision RMS that is similar to an average near (and not distance) interpupillary distance.
PURPOSE: To determine whether the optical quality of near-vision ready-made spectacles (RMS) reaches the quality assurance levels required by the international standard ISO 16034:2002. METHODS: A total of 322 near-vision RMS of powers +2.50, +3.00, and +3.50 DS were randomly selected from high street stores in North East England. Assessments of the optical quality of the RMS were made, and the results were compared against the standards included in ISO 16034:2002 and the more lenient standards used to assess RMS in low-resource countries. RESULTS: Forty-eight percent of the 322 near-vision RMS failed to provide the optical quality required by international standards, with 62% of the +3.50 DS spectacles failing the requirements. This was principally due to a high prevalence of induced horizontal (60%) and vertical prism (32%) beyond the tolerance levels stipulated in ISO 16034:2002. The figures were similar when the more lenient standards used to assess RMS in low-resource countries were used due to RMS centration distances that were too large. CONCLUSIONS: There is a large prevalence of significant amounts of induced horizontal and vertical prism in higher powered near-vision RMS such as +3.50 DS. Given that the need for high-powered RMS indicates the presence of hyperopia and/or age-related eye disease in addition to presbyopia, it may be appropriate to restrict the sale of RMS to optical powers of +1.00 to +2.50 DS, which would contain much fewer errors. We also strongly recommend that manufacturers use a centration distance for near-vision RMS that is similar to an average near (and not distance) interpupillary distance.